Process of making acid-resistant molded articles containing organic fibers, resorcinol residue and asphalt



PROCES F ltdAKllNG A CllEJ RESETANT MQLDED ARTRCLES tCtlN'llAllNlN G @RGANHQ FliilIERS, RESURCKNQ L RESEDUE AME ASPLt-EALT Loren J. Miller, Akron, il' hio, assignor to American Rubber Company, New York, N. Y., a corporation of New York No Drawing. Application May El, 1952, Serial No. 289,215

4 Claims. (tCl. Edd-17.2)

The present invention relates to a process of making acid-resistant molded articles. More particularly, the present invention relates to the compounding of a composition which is especially useful in the making of molded battery containers, such as the one-piece containers used for storage batteries and which provide a plurality of cells, in each of which electrolytic action may take place. Such battery cells are commonly filled with an electrolyte, comprising an aqueous solution of sulphuric acid.

The present invention is related to my prior and copending application, Serial No. 232,047, filed lune l 1951, and having the same title as the present application. My said copending application relates and is restricted to a composition for the purposes aforesaid, articles made therefrom and processes for making such articles, wherein the composition always includes either resorcinol or phloroglucinol, or both. The present application uses in lieu of either or both these materials, a material which will be designated herein as RM 441 and which material is described in greater detail hereinafter. The line of division between these two cases is based upon these principles.

The present invention is an improvement over the pertinent prior art as set forth in the following patents: Woodley, No. 1,156,122, issued October 12, 1915; Lukens, No. 1,752,917, issued April 1, 1930 and Dilleha No. 2,501,995, issued March 28, 1950. The early prior art, which included a disclosure of a bituminous binder coupled with a substantially acid-resistant filler and also with some vegetable fiber, such as paper scraps or cotton, was subject to the objection that in the course of time, the acid of the electrolyte atacked the vegetable fibers in such a way that the acid penetrated into a wall formed of the compositions in question. Tests have shown, for exam ple, that the penetration of acid in a period of twentyeight days at 150 F. was about inches per ASTM 13639-491" test method. Inasmuch as partition walls between adjacent cells may be of the order of magnitude of inches in thickness, the penetration of 7 inches from each direction toward the center left an unattached partition only 9 inches in thickness in the center. This relatively thin portion of the partition was easily cracked due to its weakened condition, with the result that a short circuit was formed between the adjacent electrolyte baths, elfectively terminating the useful life of the battery. While it is recognized that the temperature in question (used for test purposes) is somewhat higher than that customarily met with in ordinary use, at least in these climates, the time period at which the penetration test was made is also much shorter than the intended useful life of a battery. The test was and still is, therefore, considered characteristic of the effectiveness of the compositions as battery container material.

Natural or artificial fibers of organic material, particu larly cellulosic fibers, for example, paper scraps, cotton linters, or fabric reclaimed from used tires or other similar articles, are a desirable and relatively cheap ingredient,

States Patent 0 F 2,753,312 Fatented July 3, 1956 providing a desired mechanical strength to the composition in use. It is, therefore, a general object of the present invention to protect this strengthening material so as substantially to reduce, if not Wholly to eliminate, the penetration of acid into a wall formed of such a composition, and hence greatly to increase the useful life of a battery having a container made of the composition forming the subject matter of the present invention.

, The present invention, therefore, may be summarized as an improvement in the compounding or preparation of a composition, usually using the basic ingredients of the prior art aforesaid, i. e., asphalt; a fibrous material, at least a substantial part of which is of an. acid-attackable nature; and usually, but not always, an acid-resistant mineral filler; all in substantially the proportions which have become standard in the commercial. field, as taught in these several patents, for a period of many years. The present invention also includes compositions omitting the mineral filler which has been conventionally used as aforesaid in the prior art, and which may now be omitted, for certain purposes at least, when using the RM 441 of the present invention.

These basic materials, i. e., the asphalt, fiber and filler (if used) are now used in conjunction with a new protective material, which is supplied to and admixed with the other materials in the proportions of about 1%% to about 10%, and preferably from about 2 /z% to about 5% by weight of the total of the asphalt plus the fiber ingredients of the composition. In accordance with the present invention, the essential active ingredient of the protective material is the material known as RM 441, which will be later defined in detail, this ingredient being present to the extent of about 1%% to about 6% by weight of the total Weight of the asphalt plus the fiber ingredients in the composition. Additional materials may be used as a part or all of the protective material, i. e., in addition to the RM 441 aforesaid. Such additional materials may be considered as extenders, softeners, or both, and may also partake of the characteristics of plasticizers. The preferred material of this class, which is believed to act both as an extender and as a softener, is monomeric furfuryl alcohol. Other materials which may be used as softeners or plasticizers will be set forth in detail hereinafter. It will be understood, however, that the RM 441 may be used as the sole constituent of the protective material and the desired results of the present invention obtained.

During the course of the research, leading up to the present invention, a large number of materials were tried as a protective material, singly or in combination with one another. A relatively few of. these materials so tried had any desirable effect at all, this subject matter being outlined in some detail in my copending application, Serial No. 232,047 aforesaid. In accordance with that application, the only materials which were found to be fully operative, were resorcinol and phloroglucinol. The present invention discloses an additional and somewhat different material, which is useable alone or in conjunction with other materials (which per se are not effective to obtain desired results), namely, RM 441. The present invention, therefore, is intended to cover the use of RM 441 alone or in conjunction with one or more other materials as hereinafter set forth in detail.

(Ionsidering now the details of compositions, in accordance with the present invention, such compositions consist substantially of the following ingredients: (a) asphalt, acting as a binder, (b) a strengthening fiber, a substantial portion at least of which is of an acidattackable, organic nature, (0) a protective material for protecting the composition as a whole, and particularly the acid-attachable fiber ingredient thereof, from attack by acid, such as sulphuric acid, with which the final article formed from the composition may be brought into contact, and (d) the balance of the composition, if any, consisting essentially of an acid-resistant mineral filler.

These several ingredients willnow be discussed in de tail as to their characteristics and amounts to be used.

(a) The binder material or asphalt in this case may be of various compositions, such as various manufactured asphalts, pitches, or mixtures thereof, the particular composition not being critical as far as is now known. It is contemplated that the asphalt ingredient functions mechanically to tie or bind the other materials together into a substantially homogeneous composition in use. Asphaltic compositions in accordance with the prior art are satisfactory for use as this ingredient of the composition. These materials may be natural asphalts or those remaining from oil refining operations after the removal of the more volatile portions, or may be derived from coal tar. They may also include pitches of various kinds.

It has been found that the material set forth in detail in the patent to Spelshouse et al., No. 2,455,709, issued December 7, 1948, and assigned to Socony-Vacuum Oil Company, Incorporated, is a satisfactory material. The material coming within the specific definition given in this patent as set forth in the claims thereof, and which waspurchased from the assignee of record of that patent, was in fact used as the asphalt ingredient in all the tests hereinafter given as examples in the present application. It has also been found that the specifications set forth for the asphalt in claim 1 of this Spelshouse et al. patent can be varied to provide a slightly harder type asphalt, which has now been adapted for commercial-use by the owners of the present application. The differences involve the change of the ball and ring softening point of the asphalt from the range given in the Spelshouse et al. patent (claim 1) to the range of 299 F. to 305 F.

In accordance with the present specifications for asphalt, there is also introduced a factor of ductility of 160 F. of 3 cm. to 6 cm. per ASTM test Dll344 with jaw separation of 0.4 inch per minute. This characteristic was not set forth, in the claim at least, of the Spelshouse et al. patent. In general, the characteristics of the asphalt are not critical, but rather will affect the corresponding characteristics of the final product. The present invention is directed primarily to the acid resistance of the final product, which appears to be a separate and distinct characteristic from any provided by variation in the asphalt ingredient.

The asphalt ingredient of the composition of the present invention should be from about 35% to about 80% by weight of the entire composition. In the event that an amount of filler is used comparable in general with the amount conventionally used in the prior art, the asphalt ingredient is usually in a preferred range of about 38% to about 55% by weight of the entire composition and the filler, an amount up to, but rarely exceeding, the amount of asphalt by weight. Gn the other hand, in some compositions in accordance with the present invention, wherein little or no filler is used, substantially higher percentages of asphalt are used, including percentages up to about 80% by weight of the entire composition. All these limits are not narrowly critical, but are a general guide to the approximate amount of the asphalt ingredient useable for most commercial purposes, such as for the making of battery cases.

(b) The fiber used in the composition in accordance with the present invention is provided in order mechanically to strengthen the composition, by mechanically tying together the other materials present. While it is, of course, possible to use some non-acid-attackable fiber such, for example, as glass fiber in compositions of this general character, such non-acid-attackable fibers as can beused are generally more expensive than are the acidattackable fibers, which latter are usually of an organic nature. Thus, it is contemplated that the fiber which will be used, at least to a substantial extent, will be material selected from a wide variety of cellulosic fibers and also other suitable fibers of wholly synthetic origin, such as rayon, the selection usually being dictated by economic factors, rather than by the chemical characteristics of the material. For example, scrap kraft paper may be used, as may also cotton linters. Second cut cotton linters, Government grade 5 to 6, is a preferred material in this respect. It has been found that the fiber derived from used tires is eminently satisfactory for use as part, if not all, of the fiber requirements of the present composition. Inasmuch as some of these fibers may be rayon, it is a purpose of the present invention to provide a composition wherein this rayon is protected as far as reasonably possible from attack by acid. The fiber length is not particularly important, although it is contemplated that the longer length fibers will be generally somewhat superior to shorter length fibers.

The amount of fiber to be used in the composition may be varied within certain limits. In general, if a greater amount of fiber is used, somewhat larger amounts of the protective material will be required. Depending upon the physical characteristics of the protective material considered as a whole, the composition may be thereby rendered somewhat softer or harder. there are sufficient softening agents or materials combined with the RM 441 in the protective material, so that increased amounts of this protective material, considered as a whole, will tend to soften the composition in its entirety, there will thus be imposed a limit upon the amount of this protective material which may be used. For example, such a relatively soft composition, or one which is heat-softening, can be examined by a bulge test at some predetermined temperature. The tendency to bulge, however, may be offset to some extent either by controlling the characteristics of the protective material as hereinafter set forth in greater detail, or by using a relatively harder asphalt (to oppose softness), or by admixing some harder asphalt therewith.

While quite wide varieties of percentage composition as to fiber may be used, as taught, for example, in the prior art aforesaid, wherein fiber has constituted 5% to 17% by weight of the entire composition, it is usually preferred in accordance with the present invention, to use from about 7% to about 20% by weight of fiber (based upon the weight of the entire composition) as broader limits. These limits are not particularly critical, but give a general approximation of the trend of the best practice, as it is now understood. The higher ranges of these limits are useable primarily where there is little or no filler used in the composition, as hereinafter more particularly set forth. In cases where the amount of filler present approximates that conventionally used in the prior art compositions of this type, it will usually be found that the fiber content will be about 11% to about 13% by weight of the entire composition. Furthermore, whil the total amount of fiber for a desired composition should be in this range, it is contemplated that a part only of this fiber may be of an acid-attachable nature. When there is some substantial proportion of fiber in the entire composition which is of an acid-attachable nature, the necessity for the use of the protective material of the present invention arises. This necessity becomes greater if the fiber is of an especially vulnerable type such as rayon.

(c) The protective material in accordance with the present invention has as its essential active ingredient a material known as RM 441. This material will now be defined.

RM 441 is a designation given by Koppers Company to a solid resinous material, which is obtained by them as a residue remaining in the still after removing technical grade resorcinol as a distillate. A typical ultimate To the extent that.

chemical analysis of this material (the percentages given being by weight) is as follows:

Percent Sulphur 2.8 Ash 0.2

Carbon 70.8 Hydrogen 5.5 Oxygen balance Physically, RM 441 is a dark brown, brittle material having the following characteristics:

Ball and Ring softening point 80 to 88 C. Water solubility to lsopropyl alcohol solubility 94% to 98 /2% If technical grade resorcinol is heated at about 200 C., there is produced a dark colored material appearing and responding similarly to all the tests above given as to RM 441. Thus, RM 441 is believed to consist essentially of a condensation product (or mixture thereof) n derived from resorcinol under the influence of heat. It is also known, due to its origin, that RM 441 in its present commercial form contains relatively small amounts of impurities normally occurring incident to the commercial manufacture of technical grade resorcinol, for example, small or trace amounts of 3 mercapto phenol (CeHr-OH-SH).

RM 441 can be distilled at low pressure to give about 55% of a yellow oily distillate, which will partially crystallize. The crystals amount to about 60% of the distillate (33% of the original RM 441), and melt at about 136 C. These crystals, when analyzed correctly, are found to be trihydroxy diphenyl the positions of the hydroxyl groups on the two rings being unknown. The oily portion of the distillate, representing about 22% of the entire RM 441, also contains tri-hydroxy diphenyl, again with the positions of the hy droxyl groups unknown. There is also identified in this oily portion small portions of dihydroxy diphenyl, again with the positions of the hydroxyl groups unknown. The balance of the RM 441 has not been fully or positively identified, but is believed to contain further condensation products of resorcinol, similar in some respects to the trihydroxy diphenyl above referred to, and including compounds having a plurality, probably three or more, phenyl groups linked in either straight or branched chains and with some OH groups thereon. This material is believed to be created by the polymerizing or coupling action of heat upon resorcinol, eliminating water, probably similar to a linkage formed between two resorcinol molecules as follows: HOCsH4(OHH)H3C6(OI-I)2, resulting in the chaining together, in either straight or branched chains or both, of a number of the original resorcinol molecules. It is further believed that in most instances there is at least one --OH group remaining on each of the phenyl rings, although this has not been identified. Furthermore, in an end group of a chain, it seems likely that there are two hydroxyl groups remaining on the ring. For example, a compound of the kind visualized could be expressed by the formula:

Again, in this group of compounds, which is assumed to be reasonably representative of a substantial portion of the RM 441, the positions of the several remaining OH groups are unknown. It is believed that RM 441 or a material substantially equivalent and which should for the purposes of the present application be considered as RM 441, is also formed when pure resorcinol is heated to 200 C., probably due to one or more molecules of water splitting ofi', leaving in each instance a phenol ring deficient in hydrogen; then the phenol molecular deficiency is subject to attachment to another ring as well as with resorcinol per se in order to balance the molecules.

While there is herein included not only specific tech nical data which has been exactly obtained as to the characteristics of RM 441, there is also included all that is presently known of this material. It will be understood that any theory expressed herein in this connection is given for What it may be worth, and is not to be considered as specifically limiting upon the definition of the material, but that any material derived from the sources above set forth and/ or having physical and chemical characteristics generally similar to that particularly described for RM 441, is to be considered as RM 441 for the purposes of this application, including the claims appended hereto.

It will further be understood that inasmuch as RM 441 is obtained commercially as a still residue, and as the distillation operation by which it is produced may be a batch operation, the composition may differ somewhat from time to time.

441 may be briefly defined as a solid resinous material comprising a residue remaining in the still after removing technical grade resorcinol as a distillate.

. The protective material, which is used to reduce, if not wholly to prevent, acid penetration into the composition when an article formed therefrom is brought into contact with an acid, as in the normal use of a storage battery case, is an essential ingredient of a composition according to this invention. It has been found, as will be demonstrated more clearly by the examples which follow, that this protective material should be present in the final composition to the extent of about 1%% up to about it)% by weight of the total of the asphalt and fiber ingredients thereof. The percentage is considered in this way for the reason that the only other ingredient, which may be present as a class, is the filler ingredient which is a chemically inert, acid-resistant material, and which does not appear to affect the requirements for or benefits of the protective material.

As above set forth, the protective material may consist wholly of RM 441. In such an event, or even in the event that some other material is used as a part of the added protective material, the amount of RM 441" which may be present should be from about 1%% to about 6% by weight of the total asphalt and fiber ingredients.

These limits, as to the minimum amounts in each case, are determined by the approximate minimum amount necessary to afford the desired minimum protection against acid penetration, so that an article formed from the composition will be reasonably proof against attack by acid to the extent at least which is now required by the commercial art. This percentage is fairly critical as will be demonstrated by examples which follow. Amounts of the RM 441 or of the protective material as a whole, substantially less than 1%.% by weight of the total of the asphalt and fiber ingredients will not aiford the degree of resistance against acid penetration required by the industry at this time. In other words, such requirements in accordance with the test set forth above, call for an average acid penetration of little, if any, over of an inch in the time and under the conditions of the test. In other words, when a penetration of 2-3 (64ths inches) is found, the results are not commercially satisfactory in most instances and in accordance with the present commercial standards. On the other hand, a penetration of 1-2 will usually be acceptable, while a penetration of Ol is preferred.

The preferred range of composition, considering only the Rh l 441 ingredient, is usually from about il /2% to about 5% by weight, based upon the total of the asphalt and fiber ingredients.

As the percentage of RM 441 is increased substantially above about 6%, the desired results thereof (in preventing acid penetration) appear to be progressively and substantiallylessthan the minimum requirements set by the commercial art as aforesaid. Thus, while the upper limitmay be saidto be about 6%, on the same basis given above, andwhile this limit is not narrowly critical, amounts of RM' 441" substantially greater than this give substantially poorer results in terms of acid penetration and hence are not desired and are not to be considered withinthe purview of the present invention.

Due to the fact that RM 441 is a solid resinous material; which is quite hard at room temperature, it tends to make'a composition, including this material, relatively hard. As such, it may be used alone in a composition containing only asphalt and fiber, and without any mineral filler included. An example of such a composition is given hereinafter. On the other hand, due to the same physical characteristics of hardness of RM 441, it is quiteusual to admix with it some material which will tend to soften it, andin a preferred embodiment of the invention, a material acting not only as a softening agent, but also as an extender. A preferred material in this dual use class is monomeric furfuryl alcohol. Thus, a preferred'embodiment of the present invention is one in which RM 441 and monomeric furfuryl alcohol are used together, and jointly make up the protective material. As has been found in the past and as referred to in'my copending application, Serial No. 232,047, monomeric furfuryl alcohol is not useable alone as the protective material with satisfactory results. It is useable, however, in conjunction with the RM 441 as herein set forth. monomeric furfuryl alcohol are operative, in accordance with the present invention, and within the limits hereinafter set forth, a preferred proportion is about equal parts by Weight of these two materials. This proportion, however, may be biased in one direction or the other, as may be desired in view of the physical character of the other ingredients, so as to give a deisred hardness for the composition as a whole, and thus for articles formed therefrom.

Other materials which may be used in conjunction with RM 441 and which may be collectively considered as non-water-soluble plasticizers, include (but are not limitedto) the following: hydrogenated tallow fatty acid, stearine pitch, petroleum products ranging from light mineral oil through petrolatum to medium hard and hard hydrocarbon pitches, asphalts and waxes, pine tar oil, hydrocarbon oils derived from still residues, rubber hydrocarbons, linseed oil, and natural and other waxes including candelilla, montan, Japan, carnauba, ceresin and beeswax. In this connection, some of the watersoluble synthetic waxes or water-soluble softening agents are not operative, so that this group of plasticizers should be restricted to water insoluble materials.

The highlimit of about 10% given above as top limit for the protective material (which must apply to RM 441 plus at least one other material as furfuryl alcohol as it exceeds the limit for RM 441 alone as aforesaid) is again not a definite and exactly critical limit, but in this case represents about the highest amount of material of this character shown in the examples included herein. It will be understood that as the upper limits of concentration of the protective material are reached, the cost of the completed composition or articles formed therefrom is correspondingly increased, as the protective material ingredient of the entire composition is the most costly single ingredient thereof. The practical high limit, therefore, is dictated to a major extent by economic rather than technical factors. This is particularly important in forming articles such as battery cases where the conditions of economic competition are such that price is a major factor governing the composition to be used commercially.

(d) The acid-resistant filler contemplated for use in accordance with the present invention is substantially chemically inert in character and may be of any material which is relatively proof against attack by battery acid.

While various proportions of RM 441 and Among the materials, which: are presently consideredsuitable for this purpose .arepdwdered coal, powdered glass, pyrophyllite, the pulverulent material resulting from the grinding or polishing of glass, and possibly other materials of a generally similar nature. As far as is now known, this material functions in a mechanical way only.

and does not enter into the composition by any chemical reaction. As further requirements as to this material, it is desirable that this material have a small particle size, such that substantially all of it will pass through a mesh screen.

This material will be present in an amount principally determined by difference between the total of the other.

materials herein set forth and 100%. In general, there will be about 35% to 45% fillerin most compositions useable commercially in accordance withthe present invention for the making of such articles as battery cases.

Again, these limits are not narrowly critical, but depend upon the amount of other materials used and the characteristics desired in the final product, other than the characteristic of acid resistance to which the present invention particularly pertains.

It will be noted, however, that-in accordance with the. present invention, the filler ingredient of the composition is not essential in one embodiment at least of the invention which uses filler whatsoever. The invention from a broad point of view includes the use of any amount of filler up to the-balance of the composition, as dictated by the proportions of the remaining ingredients used, and.

will be found that the amount of fiber to be used should have a relation to the amount of asphalt in a weight ratio from about 1:3 to about 1:4; Once these factors have been decided upon, the amount of protective material can be determined as a desired percentage of the total weight of the asphalt plus the fiber ingredients by following the principles given above. The filler, if used, makes up the balance of the composition.

Thus, one embodiment of the present invention comprises the provision of a composition and articles formed therefrom, wherein there is no filler used whatsoever, such a composition could, for example, consist of about 77% asphalt, 19% fiber, and 4% protective material (which in this case is all RM 441). Such a material may be quite desirable in use in that it will have a very low specific gravity (about 1.14) as compared with averagespecific gravities of prior art compositions (1.45 to about 1.55). As such, compositions, excluding filler, can be formed into articles which are lighter in total weight and which may correspondingly be shipped at a lower cost. This becomes important where economics play a vital part and where the articles are produced at a substantial distance from their point of use.

A particular preferred composition, in accordance with the present invention, comprises asphalt about 42%, fiber (reclaimed from old tires) about 12%, protective material (consisting of a 5050 mixture of RM 441 and monomeric furfuryl alcohol) about 4%, and filler about 42%.

It has further been found that the use of protective ma terials inaccordance with the present invention serves to impart substantial protection against acid penetration, even when some or all the fiber used is rayon and/or nylon, such as is obtained from some old tires which are reclaimed. Rayonand nylon have been found in general to be more difficult to protect against acid penetration than is cotton or natural cellulosicfibers used as such,

but is protected to a very substantial extent at least by the protective material of the present invention.

The theory of the operation of protecting the composi' tion and particularly the acid-attackable fiber ingredient thereof, by following the teachings of the present invention, is not clearly or definitely understood. There will be stated for what it may be worth, some of the theories presently considered as explaining in part at least the desirable results which are actually obtained.

Considering the protection of cotton (cellulosic fibers), it is believed that the fibers in the final product when formed into an article such as 21 battery case, are generally oriented due to the plastic flow of the material during the molding process; and that a high percentage of the individual fiber ends start at the surface of the article and extend toward the center of a wall thereof, such as a partition wall between the cells of a battery case. It is believed reasonable to assume that the tar residuum (asphalt) covering the outside ends of the fibers is quite thin, or non-existent, due to the wiping action of the molding surface. Thus, a single fiber with one end at the partition or wall surface and the other nearer to the partition or wall center, is covered by a thin film of tar residuum (asphalt) containing particles of the inert mineral filler, such as pyrophyllite and coal dust. When the sulphuric acid (such as battery acid) contacts the fiber, a reaction is believed to occur between a hydroxyl group of the cellulose and the sulphuric acid, resulting in sugar formation due to splitting off of water molecules. Sap rises in trees due to the osmotic pressure exerted by a sugar solution on the semi-permeable cellulose membranes, so that analogous result from the degradation of the cellulosic fiber in the asphalt composition by battery acid is believed to permit the sugar solution plus acid to penetrate further into the fiber and other adjacent fibers. The addition of a component compatible with the hydrophyllic material as well as with hydrophobic, hydrocarbons (asphalt) is believed to induce better association of the cellulosic fibers and the petroleum tar residuum (asphalt) and/ or to retard the action of the battery acid due to this resultant compatibility.

It is further believed that the peculiarly etfective action of RM 441 in the present case is essentially to that of resorcinol, as disclosed in my copending application, Serial No. 232,047, aforesaid, in that there is presumably present at some place or places in the molecules making up the RM 441 some double activated hydrogen atoms, such as that at the two-position in the ring in resorcinol (between the groups at the oneand three-positions to which the OH groups of resorcinol are bonded). It is considered that a nuclear hydrogen, ortho to a hydroxy group in the ring. is thereby activated. Thus, of the several hydroxy-substituted benzenes, only in resorcinol and phloroglucinol are there double activated hydrogen atoms, bonded to carbon in this way. While this reasoning applies to resorcinol and phloroglucinol, it is believed in some way also to be applicable to the RM 44-1, which appears to act in substantially the same way to protect the cellulosic fibers from attack by acid in a way and to an extent that cannot be done by inactivated or singly activated hydrogen in some of the more or less similar compounds which have been tested without comparable desirable results as set forth in my copending application aforesaid.

It is recognized that this explanation is not complete and further that it does not take into account the matter of partial replacement of some of the RM 441 by monomeric furfuryl alcohol. It is, however, the best explanation that can be given at this time. In any event, no particular theory of operation is relied upon support of the appended claims, as this case merely points out the manner in which desirable and reproducible results can and will always be obtained, and the composition and varients thereof within the limits of the present invention.

In combining the ingredients aforesaid in accordance with the present invention, any desired or usual method and/or apparatus for combining materials of this kind may be used. The order in which the materials are mixed together is not critical or vital to the success of the composition or to the method of making it. It has been found in practice that good results may be obtained by introducing all the ingredient materials aforesaid into a suitable mixer in any order and at temperatures at which these materials may be satisfactorily mixed, usually between about 300 F. and about 400 F. and preferably about 350 F, at which temperature the asphalt ingredient is reasonably low in viscosity. A thorough mixing should be eifected so as to produce a substantially homogenous mixture. This mixing is explained in some detail in the Woodley patent aforesaid, and is not per se a part of the present invention.

It may, in some instances, be desired first to mix the fiber ingredient with the protective material and then, as a second step, to blend the mixed fibers and protective material with the other ingredients. This, however, is

not essential as aforesaid.

The molding of the material may be effected in any conventional manner, for example, in the manner inwhich battery cases or other articles have been formed for many years in accordance with the teachings of theprior art, and with the commercial art generally. In the molding operation, it is often desirable to use a small amount of a mold lubricant admixed with the com position in order to assist in stripping the molded articles from one or both the molding members or dies. Such use is to be considered within the purview of the present invention.

The novel character of the present invention and the limits of usefulness thereof are demonstrated by the following examples, in connection wtih each of which there will be given an outline of the point or principle being demonstrated:

EXAMPLE I As a general example to show the eflicacy of the use of RM 441, as compared with the prior art, the following tabulated results may be given:

From the above, it will be noted that the: acid penetra tion into compositions in accordance with the present invention is very substantially below that in compositions: of the early prior art, the present compositions providing resistance to acid penetration which is satisfactory in accordance with present commercial standards, while' that of the early prior art is now considered unsatisfactory.

EXAMPLE II This example is given to show the effect of different percentages of RM 44l (this material being used alone as the protective material in the tests set out in this example). In Table II, which follows, all the tests were made using a basic composition including asphalt, 600 units by weight; fiber, 180 units by weight; and filler, 570 units by weight.

When higher percentages of RM 441 were used, still higher acid penetrations were encountered, such penetrations being never less than 45 on the same scale as that used in the Table.

From this, it may be concluded that at least about 1 4% of RM 441 is required, based upon the total of the asphalt and fiber ingredients, in order that desired resistance against acid penetration be provided. It may further be concluded that amounts of RM 441 substantially in excess of about 6% give undesired results, as the acid penetration is shown to increase with larger percentages of RM 441.

EXAMPLE III A number of tests, which are not reported numerically herein, have been conducted to determine the effect of variations in the proportion of filler used in the composition, other proportions, as far as possible, remaining substantially the same. Here again, as in my copending application, Serial No. 232,047, aforesaid, no change in acid penetration was detected with variation in the percentage of filler.

EXAMPLE IV A further group of tests, which are not reported numerically in view of the results obtained, were made to determine the effect on acid penetration of variations in the percentage of fiber in the composition, other factors remaining the same as far as possible. In this group of tests, as in the tests described under Example III, above, no substantial variation in acid penetration was detected with variation of fiber content within the limits given above. Again, these results are in conformity with the corresponding results set forth in my copending ap plication, Serial No. 232,047, aforesaid.

EXAMPLE V A further series of tests were conducted using for the most part substantially the same cotton fiber and filler composition and varying the character of the protective material from all RM 441 and no monomeric furfuryl alcohol to all monomeric furfuryl alcohol and no RM 441. The results of these tests are shown in Table III, which follows:

Table III (Percent of As- Acid Asphalt, Filler, Cotton, phalt Fiber) Pene- Test N 0. Wt. Wt. Wt. tration, Units Units Units 64th of RM441 FA an inch 53 31. 5 12. 5 4. 67 G l 53 31. 12.5 4. 55 0.12 1-2 53 31. 5 12.5 3. 92 0. 75 ]2 53 31. 5 12. 5 3. 27 1. 40 0 1 53 31.5 12. 5 2. 64 2. 03 O-l 53 31.5 12.5 1. 91 2. 70 0-1 53 31. 5 12. 5 1. 27 3. 40 1-2 43. 2 41. 2 13 1. 30 3. 43 2-3 43. 2 41. 2 l3 64 3. 98 3-3 43. 2 41. 2 l3 0 4. 63 4-5 From the above it may be concluded that percentages of RM 441 down to about 1%%, based upon the total of the asphalt plus fiber ingredients with various amounts of monomeric furfuryl alcohol, are effective to 12 produced the desired results; and that a preferred composition of these two materials, i. e., RM 441 and monomeric furfuryl alcohol, includes the preferred ratio of about equal parts by weight, with best results in this general order of magnitude.

EXAMPLE Vi This example and the data given are chosen to show the effect of progressively higher proportions in the composition as a whole of a mixture of equal parts by'weight of RM 441 and monomeric furfuryl alcohol. In these compositions, the proportions of the other ingredients necessarily had to be varied somewhat in order that the physical characteristics of the composition as a whole be practical from a commercial point of view. This will explain the variation in other ingredients. It is noted that by adding together the percentages of the two materials generally making up protective material, the last composition given in the following Table IV, is one in which over 10% protective material was present based upon the total of asphalt and fiber ingredients, while the acid penetration was still kept at a minimum. While it is presumed that still greater percentages of these materials as the protective material could be used, the tests were not carried further for the reasons set forth above; and that economic factors will serve to limit and effectively to prevent the use of greater amounts of protective material, even though such greater amounts might be efficacious from the point of view of acid penetration. The effect of different proportions of protective material is shown in the following table:

Table IV (Percent of Assphalt, Filler, Cotton, phalt-l-Fiber) Acid Test No Wt. Wt. Wt. Penetra- Units Units Units tion, 64th RM FA of an inch The present invention has b on described generally in the foregoing description; limits have been given of the use of it and bases for these limits set out. Every essential principle set forth has been illustrated by the results of actual tests which have been made. Some variations of the preferred process and composition in accordance with the present invention have been taught hcreinabove, and others will occur to those skilled in the art from the foregoing particular description. It is intended that all reasonable equivalents of the subject matter particularly disclosed shall be considered to be within the purview of the present invention and within the scope of the appended claims, which are to be construed validly as broadly as the state of the prior art permits.

What is clairned is:

l. The process of increasing the resistance to acid attack and penetration of a molded article formed from a composition having as ingredients: (a) a binder of asphalt in an amount of about 35% to about by weight of the composition, (b) a strengthening fiber in an amount of about 7% to about 20% by weight of the composition, including a substantial amount of an acid-attachable organic fiber, (c) a protective material to protect said acidattackable fiber from attack by acid with which said article may be brought into contact and in an amount of about 1%% to about 10% by weight based upon the total weight of said asphalt plus said fiber in the composition, of which about 1% to about 6% on the same basis is a solid resinous material comprising a residue remaining in the still after removing technical grade resorciriol as a distillate, said solid resinous material being a dark 13 brown, brittle material having the following characteristics:

Ball and ring softening point 80 to 88 C. Water solubility 20% to 25%. Isopropyl alcohol solubility 94% to 98 /2%.

said composition as a whole being substantially free of any material capable of catalyzing (1) said solid resinous material, (2) monomeric furfuryl alcohol, and (3) a mixture of said solid resinous material and monomeric furfuryl alcohol to the form of polymerized or condensed resins respectively, and (d) the balance of the composition consisting essentially of acid-resistant mineral filler; the relative amounts by weight of the asphalt ingredient (a) to the fiber ingredient (B) being from about 3:1 to about 4: 1; the amount of said filler ingredient (d) having a zero lower limit and an upper limit substantially equal to the amount of the asphalt ingredient (a); said process comprising the steps of blending the named ingredients in the proportions stated into the composition aforesaid, and molding an article from the composition thus formed.

2. The process in accordance with claim 1, wherein said protective material consists essentially of said solid resinous material.

3. The process in accordance with claim 1, wherein said 14 protective material consists essentially of said solid resinous material and monomeric furfuryl alcohol.

4. The process in accordance with claim 1, in which the asphalt binder constituting ingredient (a) is present in an amount of about 38% to about 45% by weight of the composition, and in which the strengthening fiber constituting ingredient (b) is present in an amount of about 11% to about 13% of the entire composition.

References Cited in the file of this patent UNITED STATES PATENTS 662,929 Gelinek Dec. 4, 1900 826,180 May July 17, 1906 1,516,469 Miller Nov. 18, 1924 1,542,615 Germain June 16, 1925 1,688,041 Forrest et al Oct. 16, 1928 2,366,049 Payne Dec. 26, 1944 2,501,995 Dillehay Mar. 28, 1950 2,599,986 Goegel et a1 June 10, 1952 2,647,091 McColgan July 28, 1953 FOREIGN PATENTS 877 Great Britain of 1915 

1. THE PROCESS OF INCREASING THE RESISTANCE TO ACID ATTACK AND PENETRATION OF A MOLDED ARTICLE FORMED FROM A COMPOSITION HAVING AS INGREDIENTS (A) A BINDER OF ASPHALT IN AN AMOUNT OF ABOUT 35% TO ABOUT 80% BY WEIGHT OF THE COMPOSITION. (B) A STRENGTHENING FIBER IN AN AMOUNT OF ABOUT 7% TO ABOUT 20% BY WEIGHT OF THE COMPOSITION, INCLUDING A SUBSTANTIAL AMOUNT OF AN ACID-ATTACKABLE ORGANIC FIBER, (C) A PROTECTIVE MATERIAL TO PROTECT SAID ACIDATTACKABLE FIBER FROM ATTACK BY ACID WITH WHICH SAID ARTICLE MAY BE BROUGHT INTO CONTACT AND IN AN AMOUNT OF ABOUT 1 1/4% TO ABOUT 10% BY WEIGHT BASED UPON THE TOTAL WEIGHT OF SAID ASPHALT PLUS SAID FIBER IN THE COMPOSITION, OF WHICH ABOUT 1 1/4% TO ABOUT 6% ON THE SAME BASIS IS A SOLID RESINOUS MATERIAL COMPRISING A RESIDUE REMAINING IN THE STILL AFTER REMOVING TECHNICAL GRADE RESORCINOL AS A DISTILLATE, SAID SOLID RESINOUS MATERIAL BEING A DARK BROWN, BRITTLE MATERIAL HAVING THE FOLLOWING CHARACTERISTICS: 